The localStorage might be full in your browser (there's a 5MB cap, 10MB in firefox). I've been working on optimizing items over the past few days to take up less space, but old items still use the old formatting and thus take up more space.
If you clean up your inventory the save should work again. I did add a check for if your save fails but that might not be working considering you're not seeing it? If you can give me a little more context around your current game state I may be able to look into it more.